This invention relates to a current supply circuit for a mining machine, particularly a drum-cutter loader having two cutting drums each independently driven by a drive motor. More particularly, the present invention relates to such a current supply circuit receiving power from a cable which is divided into two sections on the mining machine with each section arranged to supply electrical power to one of the individual drive motors for the cutter drums.
In the publication entitled "Schneidende Gewinnung mit Eickhoff-Walzenladern" by Gebr. Eickhoff Maschinenfabrik und Eisengiesserei m.b.H. there is disclosed on page 8 a drum-cutter loader mining machine in which each of two cutter drums is driven by an independent electric motor. The two electric motors are connected to an electric supply circuit of the heading by a common cable which is divided inside the machinery of the mining machine into two sections which extend one each to an electric motor for driving a cutter drum.
U.S. Pat. No. 3,633,081, assigned to the Assignee of this invention, discloses a control for the driving motor of a winch used on a drum-cutter loader mining machine to propel the machine along the mine face. The winch driving motor control is effected through the use of a three-phase controller. A first electric motor drives the cutting element on the mining machine and a second electric motor drives the winch used to advance the mining machine along the mine face. The torque and speed of the winch motor are reduced when both the cutting element drive motor is idling and when the cutting motor is overloaded. The control system operates so that as the cutting element approaches a coal seam and driven in an idling speed, the speed of the winch drive motor is relatively low. When the cutter enters the coal face and the current to the cutter drive motor increases, the speed of the winch drive motor is also increased and when the cutter drive motor is overloaded, the winch drive motor is reversed to withdraw the cutting element from the coal face and thereafter again advance the cutting element into the coal face in a step-like manner.
In a drum-cutter loader mining machine having two motors each driving an independent cutter drum, the motor coupled to drive the cutter drum which is leading in relation to the movement of the mining machine, is normally more heavily loaded than the motor coupled to drive the cutter drum which is trailing in relation to movement by the mining machine. Both motors, however, run at substantially the same speed.